vaadinTranspileDependencies fails for @JsModule, even if its not used

[Shridhad]

**Desktop

• OS: iOS (10.15.6)
• JDK version: 8
• Gradle version: 6.51
• Vaadin Plugin version: 1.3.5 and 1.5
• Vaadin version: 14.3.4

Describe the bug I am using Vaadin 14.3.4 with compatibility mode. It works fine in development mode, but when I try to run production mode, vaadinTranspileDependencies fails with the following error message

Task :web:vaadinTranspileDependencies
Performing annotation scan...
Returning default whitelisted packages...
Scanning with whitelist:
.
.
.
Scan completed. 
Javascript modules is not supported in compatibility mode.
The following classes contains @JSModule annotations
.
.
.
Please use HTML imports instead.

I am not using @JsModule anywhere in my code. However, all the mentioned classes with error do extend Vaadin components. For example. Vaadin-Dialog version 2.2.1 and Vaadin-Details version 2.1.0

Same project is working with Vaadin version 14.0.5 and Vaadin Gradle plugin 1.3.5

To Reproduce Steps to reproduce the behavior:

1. Setup project with Vaadin 14.3.4 and compatibility mode
2. Extend Vaadin components to implement a custom component
3. Run ./gradlew vaadinTranspileDependencies

Expected behavior vaadinTranspileDependencies should run successful and application should run in production mode